20 MASS. EXPERIMENT STATION BULLETIN 412 



Figure 5-B, holds about 2 gallons of liquid and is operated by a spring shut-off 

 valve connected to a J^-inch discharge pipe. The outlet of the discharge pipe 

 must be turned upward slightly so that the liquid in the pipe will not run out 

 when the valve is closed. The proper amount of liquid for treating each plant is 

 discharged by quickly raising the valve rod with the fingers while holding the 

 applicator by the bail. Comparative tests indicate that the solution can be 

 applied effectively in about one-third less time than with a bucket and dipper. 



Figure 5. Equipment for Applying Corrosive Sublimate Solution. 



A (right). Bucket and homemade dipper holding one-half cupful. A wooden bucket is 



preferable, but galvanized iron can be used if carefully washed. 

 B (left). Hand-operated applicator especially designed for applying corrosive sublimate 



solution. 



Photo by W. E. Tomlinson, Jr. 



Number and Time of Applications. — Corrosive sublimate solution was applied 

 at four periods one week apart beginning when the first eggs were found. These 

 applications were timed in 15 combinations as shown in Table 11. 



It is evident that tw^o or more applications are necessary for consistently good 

 control and that one of these applications must be made within a week after the 

 first eggs are found (first or second period). More than two timely applications 

 are unnecessary. 



The control from one application was relatively unsatisfactory and extremely 

 variable. In six years one application at the first period was more effective three 

 times, and one application at the second period three times. One application 

 at the third or fourth period (two or three weeks after the first eggs are found) 

 was definitely unsatisfactory. With one exception good control was obtained 

 from one application only when less than 80 percent of the untreated plants were 

 commercially injured. 



